The feasibility of trace and ultra-trace element determinations on microliter volumes of blood serum using resonance ionization spectroscopy (RIS) has been established in Phase I. The development of instrumentation, methodology and applications has the potential to further our understanding of the role of trace metals in premature infants. Trace element accumulation in the human fetus occurs during the last trimester of pregnancy, and premature birth interrupts this process at a critical time. Very little is known about trace element nutrition requirements in premature infants, or about the relationship of trace metals to observed dysfunctions, since the amount of blood available is less than 0.1 ml. The specific aims of this proposal are to: 1 design, fabricate and evaluate a commercial prototype instrument on RIS to determine ultramicro quantities of metals; 2) complete a study of trace metals in low birth weight (1000-2000 grams) pre- term infants; 3) develop a methodology for analytical services using ultra-micro techniques and RIS. The technology developed will provide a commercial prototype RIS instrument for ultra- trace element and isotope determinations, and the basis for service analyses for the neonatology and medical communities. The baseline study of trace metals will be the first performed with premature infants using sample sizes less than 0.1 ml.